The present invention relates to a display device.
From U.S. Pat. No. 5,414,439, a display device in a motor vehicle is already known in which an image, picked up by an infrared camera, can be projected by a display, arranged in the dashboard, via an aspherical mirror, likewise arranged in the dashboard, onto the windshield. A virtual image, which is visible for a driver in the vehicle, appears on the windshield. In this case, both the display and the aspherical mirror must be disposed in the dashboard. In addition, an opening must be provided in the dashboard for the light which is reflected by the aspherical mirror to the windshield and which is necessary for an image representation.
In contrast, the display device of the present invention has the advantage that a display device for a virtual image can be implemented in a space-saving manner in a vehicle; for because an image-forming unit is arranged in the region of the vehicle roof or in an upper region of the windshield, an arrangement of optical elements within the dashboard can be dispensed with to the greatest extent possible. In particular, it is not necessary to provide a light path within the dashboard. Therefore, it is possible to dispense with a corresponding opening in the region of the dashboard. Consequently, due to the reduced space requirements, costs when constructing the display device can be lowered. It is also possible to retrofit a display device of the present invention on a vehicle which is not designed for such a display device by its manufacturer and in which no place is provided for a light path in the dashboard. In addition, temperature problems can be avoided which can occur with an arrangement of an image-forming unit in the dashboard, since the dashboard can generally heat up particularly strongly due to direct exposure to sunlight.
It is particularly advantageous to arrange the second aspherical mirror on the dashboard in a manner that the mirror can be covered. Soiling or damage of the mirror can thereby be avoided.
Furthermore, it is advantageous to design the first or the second aspherical mirror to be adjustable by motor. Such an adjustment permits adaptation of the alignment of the first and/or the second aspherical mirror to a sitting position of a driver, so that the position of the virtual image can be optimally adjusted.
It is also advantageous to carry out this adjustment via an operating element, so that unnecessary touching of the mirror, and soiling possibly associated with it, can be avoided.
It is furthermore advantageous to design the image-forming unit as a liquid-crystal cell having a backlighting, since in this way, the image-forming unit can be implemented particularly inexpensively.
Another advantage is for the windshield to be wedge-shaped. It is thereby possible to avoid double images in the projection which are formed because, in a windshield made of safety glass, multiple refraction can take place at the individual glass layers of the safety glass. The wedge-shaped design makes it possible for these double images to fall on one another, and only one image is visible for an observer.
Moreover, it is advantageous to integrate the image-forming unit or the first aspherical mirror into an interior mirror module. Installation expenditure can thereby be further reduced, since only the interior mirror module is arranged on the windshield or on the vehicle roof. In this context, the image-forming unit may also be covered for a user by the interior mirror, and a possible disturbance to the user by a visible, image-forming unit is avoided.
It is further advantageous to cover the mirror with a foil, which reduces the visibility of the mirror without at the same time substantially influencing the reflection properties of the mirror. By this, a glare, e.g. by sunlight which falls on the second aspherical mirror, can be avoided to the greatest extent possible.